45 Better Risk Management for Underground Pipelines and Tunnels Using Sound Geotechnical Interpretation

The author has been practicing geotechnical engineering for primarily pipeline engineering projects for over 30 years and has amassed significant experience under varying site conditions from over 300 projects. He has seen many pipeline projects by either trenchless or open cut construction methods run into serious problems, disputes, arbitrations, mediations, and court proceedings when the engineer of record of the pipeline project failed to do an adequate baseline geotechnical investigation. Often the trench design, dewatering systems, shoring systems, soil support systems, bedding and backfill were inadequate due to the engineer of record not doing an adequate geotechnical analysis and existing utility mapping. These short-comings may result from too much emphasis on profit, too little time to perform all of the steps, or engineering firms allocating budgets that restrict quality engineering of the projects. The pipeline project may also fail due to soil migration. This is a common occurrence when no filter criteria are checked and when no suitable material is designed in the trench zone. Thus, the pipe loses its lateral support, becomes over-deflected, fails to meet the design criteria and in some cases even collapses. Although means and methods are the responsibility of the contractors, licensed engineering professionals simply cannot expect the contractors to construct projects properly when there are too many deficiencies in the engineers' designs, specifications, and mappings of existing utilities. It is not possible for contractors to perform miracles in the field when the engineers of record simply do not afford the standard of care expected of them by their clients. Unnecessary problems can occur when the engineering firm's revenue generation, company growth, and client relations take precedence over staffing pipeline projects with sufficiently qualified engineers. In summary, the success of the pipeline project depends heavily on knowing enough about what is in the ground, how ground conditions behave toward buried pipelines, and how to cope with difficult site conditions. The authors document some guidelines on the above issues using several case histories from their involvement in over 500 pipeline projects.